The efficacy of emapalumab was demonstrated by Rainone et al. who described a patient with relapsed/refractory Ph-like B-ALL treated with tisa-cel who had CRS that improved within the first week after infusion, then developed persistent fevers, transaminitis, and ferritin levels that increased from 3,000 to 15,000 ng/mL over 24h before rising above the detectable range along with development of hemodynamic instability, coagulopathy, worsening cytopenias, hypertriglyceridemia, and hyperbilirubinemia, as well as a high IFNγ serum concentration despite repeated dosing of tocilizumab. The gene discussed is IFNG; the disease is congenital rubella syndrome.